update docs

Signed-off-by: Nannie_wangli <annie.wangli@huawei.com>

en/application-dev/reference/apis/js-apis-connectedTag.md

+# Active Tag
+
+> ![icon-note.gif](public_sys-resources/icon-note.gif)**NOTE**<br/>
+> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.
+
+
+## Modules to Import
+
+```
+import connectedTag from '@ohos.connectedTag';
+```
+
+
+## connectedTag.init
+
+init(): boolean
+
+Initializes the active tag chip.
+
+**Required permissions**: ohos.permission.NFC_TAG
+
+**System capability**: SystemCapability.Communication.ConnectedTag
+
+- Return value
+  | **Type**| **Description**|
+  | -------- | -------- |
+  | boolean | Returns **true** if the initialization is successful; returns **false** otherwise.|
+
+
+## connectedTag.uninit
+
+uninit(): boolean
+
+Uninitializes the active tag resources.
+
+**Required permissions**: ohos.permission.NFC_TAG
+
+**System capability**: SystemCapability.Communication.ConnectedTag
+
+- Return value
+  | **Type**| **Description**|
+  | -------- | -------- |
+  | boolean | Returns **true** if the operation is successful; returns **false** otherwise.|
+
+
+## connectedTag.readNdefTag
+
+readNdefTag(): Promise&lt;string&gt;
+
+Reads the content of this active tag. This method uses a promise to return the result.
+
+**Required permissions**: ohos.permission.NFC_TAG
+
+**System capability**: SystemCapability.Communication.ConnectedTag
+
+- Return value
+  | **Type**| **Description**|
+  | -------- | -------- |
+  | Promise&lt;string&gt; | Promise used to return the content of the active tag.|
+
+- Example
+  ```
+  import connectedTag from '@ohos.connectedTag';
+
+  connectedTag.readNdefTag().then(result => {
+      console.log("promise recv ndef response: " + result);
+  });
+  ```
+
+## connectedTag.readNdefTag
+
+readNdefTag(callback: AsyncCallback&lt;string&gt;): void
+
+Reads the content of this active tag. This method uses an asynchronous callback to return the result.
+
+**Required permissions**: ohos.permission.NFC_TAG
+
+**System capability**: SystemCapability.Communication.ConnectedTag
+
+- Parameters
+  | **Name**| **Type**| **Mandatory**| **Description**|
+  | -------- | -------- | -------- | -------- |
+  | callback | AsyncCallback&lt;string&gt; | Yes| Callback invoked to return the active tag content obtained.|
+
+- Example
+  ```
+  import connectedTag from '@ohos.connectedTag';
+  
+  connectedTag.readNdefTag(result => {
+      console.log("callback recv ndef response: " + result);
+  });
+  ```
+
+## connectedTag.writeNdefTag
+
+writeNdefTag(data: string): Promise&lt;void&gt;
+
+Writes data to this active tag. This method uses a promise to return the result.
+
+**Required permissions**: ohos.permission.NFC_TAG
+
+**System capability**: SystemCapability.Communication.ConnectedTag
+
+- Parameters
+  | **Name**| **Type**| **Mandatory**| **Description**|
+  | -------- | -------- | -------- | -------- |
+  | data | string | Yes| Data to write. The maximum length is 1024 bytes.|
+
+- Return value
+  | **Type**| **Description**|
+  | -------- | -------- |
+  | Promise&lt;void&gt; | Promise used to return the result. This method returns no value.|
+
+- Example
+  ```
+  import connectedTag from '@ohos.connectedTag';
+  
+  writeNdefTag.write("010203")
+      .then((value) => {
+          // Data is written to the tag.
+          console.log(`success to write event: ${value}`);
+      }).catch((err) => {
+          // Failed to write data to the tag.
+          console.error(`failed to write event because ${err.code}`);
+      });
+  ```
+
+## connectedTag.writeNdefTag
+
+writeNdefTag(data: string, callback: AsyncCallback&lt;string&gt;): void
+
+Writes data to this active tag. This method uses an asynchronous callback to return the result.
+
+**Required permissions**: ohos.permission.NFC_TAG
+
+**System capability**: SystemCapability.Communication.ConnectedTag
+
+- Parameters
+  | **Name**| **Type**| **Mandatory**| **Description**|
+  | -------- | -------- | -------- | -------- |
+  | data | string | Yes| Data to write. The maximum length is 1024 bytes.|
+  | callback | AsyncCallback&lt;string&gt; | Yes| Callback invoked to return the operation result.|
+
+- Example
+  ```
+  import connectedTag from '@ohos.connectedTag';
+  
+  connectedTag.writeNdefTag("010203", (err, value) => {
+      if (err) {
+          // Failed to write data to the tag.
+          console.error(`failed to write event because ${err.code}`);
+          return;
+      }
+
+      // Data is written to the tag.
+      console.log(`success to write event: ${value}`);
+  });
+  ```
+
+## connectedTag.on('notify')
+
+on(type: "notify", callback: Callback&lt;number&gt;): void
+
+Registers the NFC field strength state events.
+
+**Required permissions**: ohos.permission.NFC_TAG
+
+**System capability**: SystemCapability.Communication.ConnectedTag
+
+- Parameters
+  | **Name**| **Type**| **Mandatory**| **Description**|
+  | -------- | -------- | -------- | -------- |
+  | type | string | Yes| Event type. The value is **notify**.|
+  | callback | Callback&lt;number&gt; | Yes| Callback invoked to return the field strength state.|
+
+- Enumerates the field strength states.
+  | **Value**| **Description**|
+  | -------- | -------- |
+  | 0 | NFC disconnected.|
+  | 1 | NFC connected.|
+
+
+## connectedTag.off('notify')
+
+off(type: "notify", callback?: Callback&lt;number&gt;): void
+
+Unregisters the NFC field strength state events.
+
+**Required permissions**: ohos.permission.NFC_TAG
+
+**System capability**: SystemCapability.Communication.ConnectedTag
+
+- Parameters
+  | **Name**| **Type**| **Mandatory**| **Description**|
+  | -------- | -------- | -------- | -------- |
+  | type | string | Yes| Event type. The value is **notify**.|
+  | callback | Callback&lt;number&gt; | No| Callback used to return the field strength state. If this parameter is not specified, all callbacks associated with the specified event will be unregistered.|
+
+- Example
+  ```
+  import connectedTag from '@ohos.connectedTag';
+  
+  var NFC_RF_NOTIFY = "notify";
+  
+  var recvNfcRfNotifyFunc = result => {
+      console.info("nfc rf receive state: " + result);
+  }
+  
+  // Register event
+  connectedTag.on(NFC_RF_NOTIFY, recvNfcRfNotifyFunc);
+  
+  // Unregister event
+  connectedTag.off(NFC_RF_NOTIFY, recvNfcRfNotifyFunc);
+  ```
+
+## NfcRfType
+
+Enumerates the NFC states.
+
+| Name| Default Value| Description|
+| -------- | -------- | -------- |
+| NFC_RF_LEAVE | 0 | NFC disconnected.|
+| NFC_RF_ENTER | 1 | NFC connected.|